[GraphHopper] can I add nodes and edges to the graph on the fly?

[Peter]

Hi anonymous,


> So during the time of creating the street graph, the vehicles' nodes
will be
> considered and have their own indecies in the original nodes array.

Yes, that was what I meant.

But now I know better what you mean with this kind of car sharing. Then
it is indeed a bit different and I would assign the position to the two
nodes of the edge, but associated with a different weight in the
algorithm reflecting the precise position and skipping node(s) in case
of one ways.

The problematic is indeed very similar to the "QueryGraph vs. precise
GPS routing" discussion:
https://github.com/graphhopper/graphhopper/issues/27
https://github.com/graphhopper/graphhopper/pull/115


> sorry for the long discussion. just trying to understand the
alternatives before going further.

No problem. Interesting use case.

Regards,
Peter

On 23.07.2015 18:52, graphhopper newbie wrote:
> If I correctly understand you, this would solve the problem of adding
> vehicle representative nodes. So during the time of creating the
> street graph, the vehicles' nodes will be considered and have their
> own indecies in the original nodes array. However, what I miss is how
> to maintain the dynamic edges. when a vehicle is parked somewhere, an
> edge has to be added to connect it to the closest street node and the
> previous connecting edges have to be removed.
>
>
> Another interpretation that might be what you mean is that not to add
> vehicle nodes at all and consider the closest original street node to
> the vehicle to be the vehicle representative node and to add it to the
> data structure you mentioned earlier. if this is the case then I would
> miss some information I was planning to model using the edge
> connecting the street node and the vehicle node (still can be done
> implicitly) 
>
> sorry for the long discussion. just trying to understand the
> alternatives before going further.
>
> Regards
>
> On 23 July 2015 at 16:58, Peter <graphhopper at gmx.de
> <mailto:graphhopper at gmx.de>> wrote:
>
>     I would just mark (in a different data structure) that these nodes
>     are special e.g. in an array or (RAM)DataAccess which is more
>     complex but also storable and scales to GB.
>
>     This way you don't need to remove/re-add them and instead can just
>     remove the marker from the array. A lot easier IMO.
>
>     Regards,
>     Peter
>
>     On 23.07.2015 16:17, graphhopper newbie wrote:
>>     Thanks for the reply,
>>     The use case makes the situation dynamic. Assume that you have
>>     free floating carsharing vehicles. Let us assume that these
>>     vehicles can be parked everywehere. what I wanted to do is to
>>     periodically link these vehicles to the closest nodes in the
>>     original street graph (remove old links when vehicles change
>>     their positions). This way the vehicles will be represented as
>>     nodes in the graph and routing will be easier later. My routing
>>     algorithm has to be able to switch from walk to drive mode when
>>     such vehicle node is found. the goal is to have walk-drive-walk
>>     route in one Dijkstra run.
>>
>>     Regards,
>>
>>     On 23 July 2015 at 15:47, Peter <graphhopper at gmx.de
>>     <mailto:graphhopper at gmx.de>> wrote:
>>
>>         Hi,
>>
>>         you can, but there is currently no way to remove such edges
>>         (efficiently).
>>
>>         Another workaround would be to use the QueryGraph for this
>>         like we use to introduce virtual nodes and edges to
>>         incorporate the start+end GPS point into the graph. But never
>>         tried this.
>>
>>         Why not always add all such points to the graph, why is a
>>         dynamic scenario needed here?
>>
>>         Kind Regards,
>>         Peter
>>
>>
>>         On 23.07.2015 15:42, graphhopper newbie wrote:
>>>         Hi everybody,
>>>         I am wondering if I can add nodes and edges to the graph
>>>         after its creation in a dynamic way. I need this
>>>         functionality to deal with dynamic scenarios like
>>>         representing available bikesharing/carsharing points which
>>>         changes often. The simpist case I need is to add an edge
>>>         from a newly added node ( representing the available bike)
>>>         to the closest node in the graph and the reverse edge. i.e.
>>>         from the closest node to the the bike node. 
>>>
>>>         Thank you very much,
>>
>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/graphhopper/attachments/20150723/006ba7b3/attachment.html>